Tumor dosimetry for Cu-64 and Cu-67-labeled Mab 1A3 for radioimmunotherapy
- Mallinckrodt Inst. of Radiology, St Louis, MO (United States); and others
Clinical trials with Cu-64-benzyl-TETA-1A3 indicated this radiopharmaceutical to be an effective PET imaging agent. Preclinical studies showed that Cu-64-benzyl-TETA-1A3 is a promising agent for use in radioimmunotherapy. Tumor dosimetry has been estimated from biodistribution data obtained in a hamster model, for both Cu-64 and Cu-67-TETA-Mab 1A3, to determine residence time {tau}. S values (mean dose per unit cumulated activity) were calculated, assuming activity to be uniformly distributed within a mean tumor sphere with a weight of 0.4 g, using the formula; S{sub rk{l_arrow}rh}= 1/m{sub k} {Angstrom}{Sigma} {Delta}p {Phi}p(rk{l_arrow}rh) + 1/m{sub k} {Angstrom} {Sigma} {Delta}{sub np} {Phi}{sub np}(rk{l_arrow}rh). Values for {Delta}p and {Delta}np were obtained from MIRD decay schemes. The absorbed fractions for non-penetrating radiations were calculated by computing the average dose/center dose of a spherical {beta}{sup {minus}} particle source, and the absorbed fractions for penetrating radiations were determined using MIRD 3. Equivalent biological effects (100% tumor growth inhibition) for Cu-64 or Cu-67-1A3 were seen at different total absorbed doses to the tumor; 570 rads (2 mCi inj.) for Cu-64-TETA-1A3 compared to 1430 rads (0.4 mCi inj.) for Cu-67-TETA-1A3. This may be due to differing dose-rates (Cu-64 T{sub {1/2}} = 12.8 h; Cu-67 T{sub {1/2}} = 62h). The administered doses for equivalent biological effectiveness are proportional to the half-lives of the two radionuclides. Cu-64 and Cu-67-TETA-1A3 marrow doses were estimated (MIRD methodology) to be 0.14 and 0.63 rad/mCi, respectively, from biodistribution data in Sprauge Dawley rats, where bone and marrow were dissected. Cu-67 has been shown to be useful in radioimmunotherapy.
- OSTI ID:
- 441632
- Report Number(s):
- CONF-950603-; ISSN 0161-5505; TRN: 96:002093-0057
- Journal Information:
- Journal of Nuclear Medicine, Vol. 36, Issue Suppl.5; Conference: 42. annual meeting of the Society of Nuclear Medicine, Minneapolis, MN (United States), 12-15 Jun 1995; Other Information: PBD: May 1995
- Country of Publication:
- United States
- Language:
- English
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